<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        /* var mess;
         if(mess){
         alert("有值");
         }else{
         alert("无值");
         }*/
        //        var num = 10;
        //        console.log(num.toString(2));
        //        alert(num.toString(2));
        //Ctrl+Alt+L  格式化代码
//        var i = 3, sum = 0;
//        sum += i;
//        console.log(sum);
//        for (var i = 0; i < 20; i++) {
//
//        }
//          alert(typeof null);  //返回object
       /* var o = {};
        o.name = '张三';    //对象的动态特性*/
       function Person() {
           this.name = 'jim';
       }
       var p = new Person();
    </script>
</head>
<body>

</body>
</html>